L250ti Electrolytics in Crossover

[georgebrooke]

Hi, I am expecting the delivery of a pair of JBL L250ti speakers. In the meantime I have been looking a the design of the crossover..the first problem being to identify which was used.,
Anyway, that issue is resolved but it does lead to another question. Given that this model was supposed to be the top end of JBL domestic products, can anyone explain why it used electrolytic capacitors in the crossover? They are bypassed by film caps, and JBL advertises that fact. It was a new technique for them back in those days...but electrolytic caps everywhere else? Was it a money-saving exercise (in their top model)? Or else....?
Also has anyone an opinion about upgrading old electrolytic caps to Elna Silmic II? One argument could be that it preserves the original "voicing" of the speaker which could be lost going to the more exotic caps
Thanks for any advice.

[Ian Mackenzie]

Hi George,

https://www.stereonet.com/forums/topic/111495-jbl-250ti-charge-of-the-capacitor-brigade-d/

Referring to the schematic my suggestion is to first look at the capacitors in series with L102, L104 and L3.

Looking closely at the schematic the technique was to bypass with smaller capacitors. This works quite well but it’s not as good as charge coupled capacitors.

The reason JBL did the NP capacitor is due to the number of capacitors in this large crossover which was expensive to manufacture in production. Also for space reasons a charge coupled crossover topology would be physically much larger.

If you do some searches there are sone old threads on the subject of charge coupled crossover fit the L250TI. It would be expensive and you are best advised to build new networks.

I would avoid the Silmic capacitors as they are prone to leaking.

You may might consider better quality polypropylene capacitors such as Clarity Caps.
One combination that is very effective is the Clarity Cap SA range bypassed with an Audience Auricap 0.01 uF. I have personally used this combination and you have to spend a lot of money to do noticeably better.

[georgebrooke]

Hi George,

https://www.stereonet.com/forums/topic/111495-jbl-250ti-charge-of-the-capacitor-brigade-d/

Referring to the schematic my suggestion is to first look at the capacitors in series with L102, L104 and L3.

Looking closely at the schematic the technique was to bypass with smaller capacitors. This works quite well but it’s not as good as charge coupled capacitors.

The reason JBL did the NP capacitor is due to the number of capacitors in this large crossover which was expensive to manufacture in production. Also for space reasons a charge coupled crossover topology would be physically much larger.

If you do some searches there are sone old threads on the subject of charge coupled crossover fit the L250TI. It would be expensive and you are best advised to build new networks.

I would avoid the Silmic capacitors as they are prone to leaking.

You may might consider better quality polypropylene capacitors such as Clarity Caps.
One combination that is very effective is the Clarity Cap SA range bypassed with an Audience Auricap 0.01 uF. I have personally used this combination and you have to spend a lot of money to do noticeably better.

Hi Ian,
Nice to hear from you again,
Your advice is very useful...but I can't apply it until I get the speakers, which are trapped in Brussels right now. I was interested in charge-coupled, but I was put off by some of the comments from people who had actually tried it. The exact spec of the speakers has also been interesting. Mine are the gloss Black Classic models, but behind that name there appears to be several "sub models". We shall see when I open the box.
As an aside, I got my son to collect my speakers from Maastricht....he lives in Brussels and owns a set of Tannoy speakers. However, he was so impressed with the sound from the JBL speakers that he went out and purchased a set of 4313B speakers. They are about as old as he is and still bettering many modern (and more expensive) speakers.
All the best

George

[BMWCCA]

However, he was so impressed with the sound from the JBL speakers that he out and purchased a set of 413B speakers. They are about as old as he is and still bettering many modern (and more expensive) speakers.George, should that have been 4313B? Just curious.

[georgebrooke]

George, should that have been 4313B? Just curious.
Yes...you got me..it should have been 4313B
And very nice they are too!

George

[Robh3606]

I was interested in charge-coupled, but I was put off by some of the comments from people who had actually tried it.

I have built a pair of CC L250Ti Jubilee crossovers and they are large and expensive. I would see how what you have now sounds before making any changes. It's a subtle change not mind blowing and it effects low level clarity takes some of the "haze" away. The last 10 % kind of thing.

Rob :)

[Ian Mackenzie]

Hi George,

The charge coupled crossover with Solen 250 volt Fast Caps bring out a lot of transient detail.

If some people are reporting issues it’s with their source equipment or amplification.

Years ago people complained about the 2307/2308 lens. Same problem.

So, you need to think about that in terms of the voicing of your source components and amplification.

There’s an art to voicing a system so it’s emotionally engaging but for the right reasons.

What l have found is even stock Legacy system shine with charge coupled network but the source amplification needs to be AAA. You can’t make a silk purse out of a sour’s ear as they say.

I mainly listen to vinyl with a Keseiki Purple Heart cartridge or an Ortofon Black on a VPI Prime TT with a JC3 phono preamp, JC2 preamp and JC power amplifiers. (Parasound). I got out of Pass labs in the end because they were too bright X250.5) with the JBLs which by virtue of the metal compression driver diaphragms are analytical. The older Aleph series or the AX100 were much better with the right balance of detail and tonal density. I currently stream with a Lumin.